T21 and FRU 19K4655 RAM

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joester · #1 Post by **joester** » Thu Jan 10, 2008 5:28 pm

Recently acquired a 256MB RAM module. My T21 has 256 in it now.

I opened up the hatch, popped out module 1 (128MB) and popped in the new 256 thinking I would have 384 MB available. On boot, I entered the BIOS settings, and lo and behold, 384 MB!
Restart and it stalls with an error stating the PCI.SYS file is missing or corrupt, reboot with original installation disc and select option "R" - yada yada yada..
Put original back in, XP starts right up, no errors.

Why would the PCI.SYS file be misidentified or not recognized depending on the RAM module?

I know only "some" PC133 RAM will work in these T2x series, but the BIOS seems to identify if just fine.

Joe

BillD · #2 Post by **BillD** » Thu Jan 10, 2008 6:05 pm

Your new RAM stick is either bad or not compatible..

When you get a missing or corrupt .sys error on boot up 99% of the time it;s the RAM...

#3 Post by **Harryc** » Thu Jan 10, 2008 6:16 pm

Joe, run memtest86 from a diskette.

joester · #4 Post by **joester** » Thu Jan 10, 2008 10:04 pm

Wouldn't go past test 2, but the errors show as being on the 128MB, not the 256.

Since both 128's pass together, I'm wondering if it's reading like that because the 256 is 133mhz and the 128's are 100mhz.

Regardless, it won't boot up on only the 256, so it must be bad or have an incompatability of some sort like Bill indicated. I'll have to hang onto it until I have another system i can try it in.

Thanks!

Joe

#5 Post by **Harryc** » Thu Jan 10, 2008 10:07 pm

I had the exact same problem in a T21 with a stick of PC133 I got yesterday. Returned it and ordered up another stick of PC100.

clayts · #6 Post by **clayts** » Fri Jan 11, 2008 12:06 am

19K4655 is incompatible for the T20,21,22 - it can only be used in the T23. That's because it's a high density module - you need a low density module.

The sticky thread at the top of this page on cheap 256MB definitely helped me - make sure any sticks of PC133 SODIMM SDRAM you buy are CL2 and are 32Mx64 or they will not work.

#7 Post by **Harryc** » Fri Jan 11, 2008 6:00 am

Low density PC133 is no guarantee that it will work in a T20,21,22. In the situation I mentioned above I was using low density (16 chips) Kingmax PC133. It was CL3 though. Maybe that was the problem. Any recommendations for a specific manufacturer/model of CL2 PC133 that definately works in a T20/21/22 ?

clayts · #8 Post by **clayts** » Fri Jan 11, 2008 2:02 pm

I got a Microtek one on eBay UK for £13 - these are the ones Crucial sell I believe - there's an exact serial number in the 256MB sticky thread at the top of this page - ends 13EE I seem to recall.

Yes, CL3 is the issue - it has to be CL2 PC133, which is very hard to find on eBay for a reasonable price - seems vendors know they can charge a premium for it

#9 Post by **Harryc** » Fri Jan 11, 2008 3:32 pm

ct32m64s4w7e is Crucial PC133, CL2.

#10 Post by **rkawakami** » Fri Jan 11, 2008 5:04 pm

I don't believe that CL2 is necessary in the T20-T22 systems. I have a T22 running with two 128MB PC133 CL3 modules, a Hynix HYM71V16M635AT6-H and an Elpida MC-4516CD642XS-A75. I know your original concern is about 256MB modules, but size shouldn't matter here.

#11 Post by **Harryc** » Fri Jan 11, 2008 5:14 pm

"I think the system is locked into using a specific timing. What is important when using PC133 modules is that you use ones marked CL2 and not CL3. This has to do with what is called the "CAS Latency" of the memory access. Lower numbers are faster parts. Your current PC100 module should be CL2. Whatever else you install should also be CL2."

By Ray Kawakami in this thread

Why are you confusing me oh Jedi master

Website · #12 Post by **tfflivemb2** » Fri Jan 11, 2008 5:38 pm

Harryc wrote:Why are you confusing me oh Jedi master

Could be the additional experience that Ray has gained in the 1.5 years since the post that you referenced. Maybe he figured out that it was quite accurate.

Now, having said that...I, too, would like to know the answer to this, because I am confused as well?!?

#13 Post by **rkawakami** » Fri Jan 11, 2008 6:58 pm

Ouch!, that one came back to bite me, didn't it?

Hmm... must go off to inspect my systems again.

Padawan, has learned his teachings very well... the circle is now complete...

edit: Okay, back after reading that thread and looking for several others....

At that time (Jul 06) I was under the impression that the T20 system (and by inference, all other PC100 systems using the 440BX chipset) were locked into a particular memory timing, that being CL2. Thus my recommendation that the user stick with CL2 modules. This appears now to be my error. Looking at my running 600X systems, they are populated by 128MB and 256MB CL2 sticks. However, when I run the CPU-Z utility, it reports a 3 clock CAS latency. Doing the same thing on a T21 (with two 256MB PC100 CL2 modules) and CPU-Z also reports CL3. Installing the two 128MB, low density, PC133 CL3 modules as reported above from the T22 into both the 600X and T21 works fine.

I seemed to have recalled talking about this recently and I was finally able to track it down:

http://forum.thinkpads.com/viewtopic.ph ... 666#319666

Also, for 600E, and possibly other PC66 systems, the CAS latency should be CL2 based upon what I saw with some modules from mudhead:

http://forum.thinkpads.com/viewtopic.ph ... 151#232151

I will correct the post that Harryc referred to in case someone reads through that thread. Thanks for catching that!

Website · #14 Post by **tfflivemb2** » Sat Jan 12, 2008 8:54 am

rkawakami wrote:Ouch!, that one came back to bite me, didn't it?

With the help that you have given...I am sure that we can find it in our hearts to forgive you...somehow...

joester · #15 Post by **joester** » Sat Jan 12, 2008 9:48 am

So it won't run based on the high density, but might be ok?

T21 and FRU 19K4655 RAM

T21 and FRU 19K4655 RAM

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